Damper structure for clutch

ABSTRACT

A clutch includes a clutch housing configured to hold a clutch plate, and a clutch gear configured to transmit rotary drive power to the clutch housing via a damper. The clutch housing has a rib that regulates a position, of the damper, in an axial direction. The dampers are accommodated in accommodation holes that are spaced from each other in a circumferential direction of the clutch gear. The rib is formed in an annular shape so as to be aligned with the accommodation holes.

CROSS REFERENCE TO THE RELATED APPLICATION

This application is based on and claims Convention priority to Japanesepatent application No. 2014-111344, filed May 29, 2014, the entiredisclosure of which is herein incorporated by reference as a part ofthis application.

BACKGROUND OF THE INVENTION

Field of the Invention

The present invention relates to a damper structure of clutches for usein internal combustion engines for vehicles, mainly for saddle-ridingtype vehicles such as motorcycles, three-wheeled vehicles, andfour-wheeled buggies.

Description of Related Art

As clutches for use in internal combustion engines of vehicles, it hasbeen known that a clutch that has a damper, for damping torque, isinterposed between a driving-side rotary member and a driven-side rotarymember, and absorbs variation in torque that is generated in a powertransmission system for an internal combustion engine (for example, JPExamined Utility Model Publication No. 03-002031).

In a structure having such a damper, a deformation margin for the damperneeds to be assuredly provided in order to reduce shock. However, in acase where an axial clearance between the damper and the driven-siderotary member is increased so as to assuredly obtain such a deformationmargin, an axial position of the damper is rendered to be unstable.Further, in a case where the axial clearance is increased, the outercircumferential surface of the damper to be pressed by a clutch gear ofthe driving-side rotary member is offset in the axial direction, and aportion of the outer circumferential surface of the damper may not bepressed, which may increase a load per unit area of the outercircumferential surface of the damper accordingly. Therefore, a width(dimension in the axial direction) of the clutch gear needs to beincreased, which leads to increase in weight.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a damper structure, forclutches, which allows a deformation margin for a damper to be assuredlyprovided while stabilizing a position, of the damper, in the axialdirection.

In order to accomplish the above object, a damper structure for a clutchaccording to the present invention includes: a clutch housing configuredto hold a clutch plate; a clutch gear configured to transmit rotarydrive power to the clutch housing via a damper; and a rib that regulatesa position of the damper in an axial direction.

In the above configuration, since the clutch housing has the rib thatregulates the position of the damper in the axial direction, theposition of the damper in the axial direction is stable. Further, aclearance in the axial direction is formed between the damper and therib. Therefore, when the damper absorbs shock, the damper is deformedtoward the clearance around the rib, and thus, a deformation margin isassuredly obtained to exhibit damper effect, and also deterioration ofthe damper due to compressive force is reduced to maintain the dampereffect. Further, the rib allows the position, of the damper, in theaxial direction to be stable, and therefore, the widthwise dimension(the dimension in the axial direction) of the clutch gear need not beincreased. Thus, the weight is not increased.

In the preferred embodiment of the present invention, a plurality of thedampers are accommodated in a plurality of accommodation holes that arespaced from each other in a circumferential direction of the clutchgear, and the rib is formed in an annular shape so as to be aligned withthe plurality of accommodation holes. In this configuration, the rib canbe easily formed.

Where the rib is formed in the annular shape, a widthwise dimension ofthe rib in a radial direction is preferably set within the range of 1/20to ⅕ of an inner diameter of the accommodation holes. When the widthwisedimension of the rib in the radial direction is less than 1/20 of theinner diameter of the accommodation hole, the position of the damper inthe axial direction is unstable. On the other hand, when the widthwisedimension of the rib in the radial direction is greater than ⅕ of theinner diameter of the accommodation hole, the deformation margin for thedamper may not be sufficient.

Where the rib is formed in the annular shape, the clutch housingpreferably has engagement projections that engage with engagement holesformed at center portions of the dampers, and the rib is preferablyformed so as to connect to the engagement projections. In thisconfiguration, the dampers can be stably supported in the clutchhousing. Further, root portions of the engagement projections arereinforced by the rib.

Where the rib is formed in the annular shape, a projection height of therib from the clutch housing is preferably set within the range of 0.5 mmto 1.5 mm. When the projection height is less than 0.5 mm, thedeformation margin for the damper may not be sufficient. When theprojection height is greater than 1.5 mm, the size of the clutch isincreased.

Any combination of at least two constructions, disclosed in the appendedclaims and/or the specification and/or the accompanying drawings shouldbe construed as included within the scope of the present invention. Inparticular, any combination of two or more of the appended claims shouldbe equally construed as included within the scope of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

In any event, the present invention will become more clearly understoodfrom the following description of preferred embodiments thereof, whentaken in conjunction with the accompanying drawings. However, theembodiments and the drawings are given only for the purpose ofillustration and explanation, and are not to be taken as limiting thescope of the present invention in any way whatsoever, which scope is tobe determined by the appended claims. In the accompanying drawings, likereference numerals are used to denote like parts throughout the severalviews, and:

FIG. 1 is a longitudinal cross-sectional view of a clutch having adamper structure according to a preferred embodiment of the presentinvention;

FIG. 2 is a longitudinal cross-sectional view of a clutch housing of theclutch;

FIG. 3 is a front view of the clutch housing as viewed in the axialdirection;

FIG. 4 is a longitudinal cross-sectional view of a clutch gear of theclutch;

FIG. 5 is a front view of the clutch gear as viewed in the axialdirection;

FIG. 6 is a front view of a damper of the clutch as viewed in the axialdirection;

FIG. 7 is a longitudinal cross-sectional view of a main portion of theclutch;

FIG. 8 is a rear view of a portion shown in FIG. 7 as viewed in theaxial direction;

FIG. 9 is an enlarged longitudinal cross-sectional view of a mainportion of the damper structure; and

FIG. 10 is a front view of a conventional damper as viewed in the axialdirection.

DESCRIPTION OF EMBODIMENTS

Hereinafter, a preferred embodiment of the present invention will bedescribed with reference to the drawings. FIG. 1 is a cross-sectionalview of a clutch having a damper structure according to a preferredembodiment of the present invention.

A clutch 2 is in the form of a friction plate clutch, and is disposedbetween an engine E and a transmission T of a vehicle such as amotorcycle, so as to connect or disconnect power, of the engine E, to betransmitted to the transmission T. More specifically, the clutch 2having a clutch gear 10 is mounted to a main shaft MS of thetransmission T, and the clutch gear 10 meshes with an output gear OGmounted to a rotation shaft of the engine E. The main shaft MS isspline-fitted to an output tooth portion 24 of the clutch 2, and isconnected to the clutch 2 so as not to rotate relative to each other.

A clutch housing 6 is connected to the clutch gear 10 of the clutch 2via a damper 8, and a plurality of friction plates 5 are supported on anouter circumferential portion of the clutch housing 6 so as to bemovable in the axial direction of a shaft center C. Further, a clutchhub 9 is disposed, on an inner circumferential side of the clutchhousing 6, so as to connect to the main shaft MS, and a plurality ofclutch plates 4 are disposed, on the outer circumference of the clutchhub 9, so as to be movable in the axial direction of the shaft center C.The clutch plates 4 and the friction plates 5 are aligned alternately inthe axial direction.

A pressing plate 7 is disposed so as to sandwich the friction plates 5and the clutch plates 4 between the clutch hub 9 and the pressing plate7. By the pressing plate 7 being pressed toward the clutch hub 9 by aclutch spring 11, the clutch 2 enters a connecting state, and rotarydrive power of the engine E, before being transmitted to the main shaftMS of the transmission T, is transmitted to the clutch 2 via the clutchgear 10 and the damper 8. Furthermore, a push rod (not shown) is pushedin the axial direction of the shaft center C (rightward in FIG. 1)according to a driver operating the clutch, whereby the pressing plate 7is moved rightward against the clutch spring 11, so that the clutch 2enters a disconnecting state to disconnect transmission of torque fromthe clutch 2.

FIG. 2 is a longitudinal cross-sectional view of the clutch housing 6,and FIG. 3 is a rear view of the clutch housing 6 as viewed from theleft side III in FIG. 2. The clutch housing 6 is made of an aluminiumalloy, and has a plurality of engagement projections 16 that aredisposed on one end surface 6 a of the clutch housing 6 and project inthe axial direction as shown in FIG. 2. The engagement projections 16are equally spaced from each other in the circumferential direction ofthe clutch housing 6. Each of the engagement projections 16 has, at itsradial center portion, a rivet insertion hole 18 that is a through holeextending in the axial direction.

Furthermore, on the one end surface 6 a of the clutch housing 6, a rib20 that regulates a position, of the damper 8, in the axial direction isformed. The rib 20 is formed so as to connect to the engagementprojections 16, that is, connect to root portions of the engagementprojections 16. The rib 20 is formed in an annular shape so as to beconcentric with the clutch housing 6 as shown in FIG. 3. The rib 20 andthe engagement projections 16 are integrally formed with the clutchhousing 6. Two or more ribs 20 may be aligned in the radial direction.

FIG. 4 is a longitudinal cross-sectional view of the clutch gear 10.FIG. 5 is a front view of the clutch gear 10 as viewed from the rightside V in FIG. 4. The clutch gear 10 is made of a steel, and has aninput tooth portion 22, having a large diameter, into which power of theengine E is inputted. As shown in FIG. 5, the clutch gear 10 has aplurality (eight in the present preferred embodiment) of accommodationholes 26 formed so as to be spaced from each other in thecircumferential direction. The accommodation holes 26 penetrate throughthe clutch gear 10 in the axial direction as shown in FIG. 4. As shownin FIG. 8, the rib 20 of the clutch housing 6 is formed in such anannular shape as to be aligned with the center of each of the pluralityof circular accommodation holes 26 when the clutch housing 6 and theclutch gear 10 overlap each other.

FIG. 6 is a front view of the damper 8 as viewed in the axial direction.The damper 8 is made of, for example, a rubber such as an NBR (nitrilerubber). The damper 8 is substantially disk-shaped and has anon-circular engagement hole 28 formed at the center portion thereof.The engagement hole 28 of the present preferred embodiment issubstantially a D-shaped oval or long hole that is elongated in a clutchradial direction D1. The damper 8 has a front side portion 32 and a rearside portion 30, or a portion 30 at a trailing side in a rotationaldirection, to which the rotary drive power P from the clutch gear 10 isapplied, such that the engagement hole 28 is disposed between the frontside portion 32 and the rear side portion 30. A thickness t1, of therear side portion 30, in a circumferential direction D2 is set so as tobe greater than a thickness t2, of the front side portion 32, in thecircumferential direction D2.

First cutout portions 34, 34 are formed on the outer side and the innerside, respectively, of the rear side portion 30, in the clutch radialdirection D1. Each first cutout portion 34 is recessed, toward an axialcenter A of the disk DK, from the outer circumference of the disk DK,that is, from an outer circumferential surface 35 obtained by maximumdiameter portions of the damper 8 being connected. A minimal distance d1between the first cutout portion 34 and the engagement hole 28 is set soas to be smaller than a distance d2 between the engagement hole 28 andthe outer circumferential surface 35 of the disk DK. A portion P1 of thefirst cutout portion 34, at which the minimal distance d1 is obtained,is positioned in the rear of a rear edge 28 a of the engagement hole 28.The rear edge 28 a of the engagement hole 28 extends almost linearlyalong the radial direction D1 of the damper 8. The minimal distance d1portion has the smallest widthwise dimension as viewed from the front ofthe damper 8 in the axial direction in FIG. 6.

Second cutout portions 36, 36 are formed on the outer side and the innerside, respectively, of the front side portion 32 of the damper 8, in theclutch radial direction D1. Each second cutout portion 36 is alsorecessed from the outer circumference 35 of the disk DK toward the axialcenter A of the disk DK.

FIG. 7 is a cross-sectional view illustrating a state where the clutchplates 4, the friction plates 5, the pressing plate 7, and the clutchhub 9 are removed in the state shown in FIG. 1. FIG. 8 is a front viewas viewed from the left side VIII in FIG. 7. A plurality (eight in thepresent preferred embodiment) of the dampers 8 are equally spaced fromeach other in the circumferential direction. The engagement hole 28 ofeach of the dampers 8 engages with the corresponding engagementprojection 16 of the clutch housing 6, and the entirety of each damper 8is accommodated in the corresponding accommodation hole 26 of the clutchgear 10. In this state, a damper holder 12 formed as a steel platemember is disposed on the side, of the damper 8, opposite to the clutchhousing 6 side, and a rivet 14 is inserted into the rivet insertion hole18 of the clutch housing 6 and then crimped to stop the damper 8 fromdropping.

As shown in FIG. 7, a clearance SP in the axial direction is formedbetween the damper 8 and the clutch housing 6 in an assembled state.More specifically, as shown in FIG. 9, one end surface 8 a, in the axialdirection, of the damper 8 which faces the clutch housing 6 contactswith the rib 20 of the clutch housing 6, whereby the position, of thedamper 8, in the axial direction is regulated to form the clearance SP.

A widthwise dimension w of the rib 20 in the radial direction ispreferably set within the range of 1/20 to ⅕ of an inner diameter d3 ofthe accommodation hole 26. Further, a projection height h of the rib 20in the accommodation hole 26 from the clutch housing 6 is preferably 0.5mm to 1.5 mm.

In the above preferred embodiment, since the clutch housing 6 has therib 20 that regulates the position, of the damper 8, in the axialdirection, the position, of the damper 8, in the axial direction comesto be stable. Further, the clearance SP in the axial direction is formedbetween the damper 8 and the clutch housing 6. Therefore, when thedamper 8 absorbs shock, in the circumferential direction, of the clutch2, the damper 8 is deformed toward the clearance SP around the rib 20,and thus the deformation margin is assuredly obtained to exhibit dampereffect, and also deterioration of the damper 8 due to compressive forceis reduced to maintain the damper effect.

Even in the case of the clearance SP formed in the axial direction, ifthe rib 20 is not provided, the axial position of the damper 8 isunstable as indicated by a double dotted line 108. When the clutch gear10 collides against the damper 108 that is offset to the positionindicated by the double dotted line, a portion 135 a of an outercircumferential surface 135 of the damper 108 is not pressed by theclutch gear 10 by a wall of the accommodation hole 26, to increase aload per unit area of the outer circumferential surface 135 of thedamper 108 accordingly. In order to avoid this state, the dimension, ofthe clutch gear 10, in the axial direction needs to be increased by h,as indicated by a double dotted line 110, which increases the weight ofthe clutch gear 10 made of a steel.

In the above preferred embodiment, since the position, of the damper 8,in the axial direction is stabilized by the rib 20, the size of theouter circumferential surface 35 of the damper 8 to be pressed by theclutch gear 10 is constant, that is, the width in the axial direction isconstant. Therefore, the dimension, of the clutch gear 10, in the axialdirection need not be increased, and the weight of the clutch gear 10 isnot increased.

As shown in FIG. 3, since the rib 20 is formed in an annular shape so asto be aligned with the plurality of accommodation holes 26, the rib 20can be easily formed by molding.

Since the rib 20 shown in FIG. 3 is formed so as to connect to theengagement projections 16 of the clutch housing 6, the damper 8 can bestably supported in the clutch housing 6. Further, the root portions ofthe engagement projections 16 are reinforced by the rib 20.

The widthwise dimension w, of the rib 20, in the radial direction asshown in FIG. 9 is set within the range of 1/20 to ⅕ of the innerdiameter d3 of the accommodation hole 26. When the widthwise dimensionw, of the rib 20, in the radial direction is smaller than 1/20 of theinner diameter d3 of the accommodation hole 26, the position, of thedamper 8, in the axial direction is unstable. On the other hand, whenthe widthwise dimension w, of the rib 20, in the radial direction isgreater than ⅕ of the inner diameter d3 of the accommodation hole 26,the clearance SP is reduced, and the deformation margin for the damper 8may not be sufficient.

Furthermore, the projection height h of the rib 20 is set within therange of 0.5 mm to 1.5 mm. When the projection height h is smaller than0.5 mm, the clearance SP is reduced and the deformation margin for thedamper 8 may not be sufficient. When the projection height h is greaterthan 1.5 mm, the size of the clutch 2 is increased in the axialdirection.

As shown in FIG. 6, the minimal distance d1 between the first cutoutportion 34 and the engagement hole 28 is set so as to be smaller thanthe distance d2 between the engagement hole 28 and the outercircumferential surface 35 of the disk DK. Thus, when the rotary drivepower P is applied from the clutch gear 10 to the damper 8, the damper 8is likely to be deformed forward through a narrow portion between thefirst cutout portion 34 and the engagement hole 28.

FIG. 10 is a front view of a conventional damper 100 as viewed in theaxial direction. In the damper 100, a minimal distance d10 between afirst cutout portion 102 and an engagement hole 104 is greater than aminimal distance d11 between the engagement hole 104 and an outercircumferential surface 106 of a disk. That is, a narrowest portion P2at which the width is minimal is formed in front of the portion P1 atwhich the minimal distance d10 is obtained.

When the rotary drive power P acts on the damper 100, a rear sideportion of the damper 100 is compressed with respect to the engagementprojection 16 and greatly deformed. However, the compressive forcecannot be sufficiently absorbed at the narrowest portion P2, and isconveyed into the narrowest portion P2, whereby the force concentratesin a portion in the rear of the narrowest portion P2. As a result, acrack Cr may be generated in the rear side portion of the damper 100.

On the other hand, in the above preferred embodiment, as shown in FIG.6, the portion P1 at which the minimal distance d1 is obtained, that is,the portion P1 that is the narrowest portion is formed in the rear sideportion 30. Therefore, the compressive force can be sufficientlyabsorbed between a portion of the damper 8 positioned in the rear of theengagement projection 16 and the engagement projection 16. In addition,since the narrowest portion is not formed in front of the portion P1,the damper 8 can be easily deformed forward. As a result, generation ofthe crack Cr in the damper 8 can be avoided.

Since the first cutout portions 34 shown in FIG. 6 are recessed from theouter circumference 35 of the disk DK toward the axial center A of thedisk DK, the first cutout portions 34 can be easily formed.

Since the second cutout portions 36 are formed in the front side portion32 of the damper 8, the damper 8 can be deformed toward space formed bythe second cutout portions 36. Thus, the damper 8 is likely to bedeformed forward, and generation of the crack Cr can be reduced withenhanced effectiveness.

The present invention is not limited to the embodiment described above,and various additions, modifications, or deletions may be made withoutdeparting from the gist of the invention. Therefore, these are construedas included within the scope of the present invention.

REFERENCE NUMERALS

-   -   2 . . . clutch    -   4 . . . clutch plate    -   6 . . . clutch housing    -   8 . . . damper    -   10 . . . clutch gear    -   16 . . . engagement projection    -   20 . . . rib    -   26 . . . accommodation hole    -   28 . . . engagement hole    -   h . . . projection height of rib    -   d3 . . . inner diameter of accommodation hole    -   w . . . widthwise dimension of rib in radial direction

What is claimed is:
 1. A damper structure for a clutch, comprising: aclutch housing configured to hold a plurality of clutch plates; a clutchgear configured to transmit rotary drive power to the clutch housing viaa damper; and an annular rib provided in the clutch housing andconfigured to regulate a position of the damper in an axial direction ofthe clutch housing, the rib is a protrusion projecting, in an axialdirection, from an end surface of the clutch housing towards the damperand a tip end surface of the rib is configured to contact with an endsurface, in the axial direction, of the damper which faces the clutchhousing, wherein: the clutch housing has engagement projections thatengage with engagement holes formed in a plurality of the dampers; andthe annular rib is aligned with the engagement projections and theannular rib and the engagement projections are integrally formed withthe clutch housing.
 2. The damper structure for the clutch as claimed inclaim 1, wherein: a plurality of the dampers are accommodated in aplurality of accommodation holes that are spaced from each other in acircumferential direction of the clutch gear; and the rib is formed inan annular shape so as to be aligned with the plurality of accommodationholes.
 3. The damper structure for the clutch as claimed in claim 2,wherein a projection height of the rib in each accommodation hole is setwithin the range of 0.5 mm to 1.5 mm.
 4. A damper structure for aclutch, comprising: a clutch housing configured to hold a plurality ofclutch plates, the clutch housing having engagement projections thatengage with engagement holes formed in a plurality of dampers, whereineach of the plurality of the dampers are accommodated in a plurality ofaccommodation holes that are spaced from each other in a circumferentialdirection of a clutch gear; a clutch gear configured to transmit rotarydrive power to the clutch housing via the dampers; and an annular ribconfigured to regulate a position of the dampers in an axial directionof the clutch housing and to connect with the engagement projections,wherein the annular rib is formed in an annular shape so as to bealigned with the plurality of accommodation holes and a widthwisedimension of the annular rib is set within the range of 1/20 to ⅕ of aninner diameter of the accommodation hole.
 5. The damper structure forthe clutch as claimed in claim 4 wherein a projection height of theannular shape rib in each accommodation holes is set within a range of0.5 mm to 1.5 mm.
 6. A damper structure for a clutch, comprising: aclutch housing configured to hold a plurality of clutch plates; a clutchgear configured to transmit rotary drive power to the clutch housing viaa damper; and a rib provided in the clutch housing and configured toregulate a position of the damper in an axial direction of the clutchhousing, wherein a plurality of the dampers are accommodated in aplurality of accommodation holes that are spaced from each other in acircumferential direction of the clutch gear, and the rib is formed inan annular shape so as to be aligned with the plurality of accommodationholes, and a widthwise dimension of the rib in a radial direction is setwithin the range of 1/20 to ⅕ of an inner diameter of the accommodationhole.